The Alliance’s first report dated January 2009 (Keystone, 2009) identified 17 metrics they felt could be evaluated and were important to measuring the sustainability of current production practices. The five metrics that were evaluated thus far and included in the 2009 report are:
- Land use indicator
- Soil loss indicator
- Water indicator
- Energy use indicator
- Climate impact indicator
In this first report the alliance reported on four crops: corn, cotton, soybeans and wheat. The four crops were selected because, according to the report, they represent a majority of all crops harvested in U.S. While the report does not provide benchmarks for achieving sustainability, it does provide data for measuring improvements, or lack of progress, over time. Based on unit of production the 2009 report shows improvement has been made in most indicators for the four crops across the 20 years included in the study. This report confirms progress is being made towards increased yields utilizing fewer inputs and a more sustainable food production system. The spidergraph below shows the extent of improvement for United States production of soybeans.
The nitrogen cycle and agricultures contribution to reactive N (Nr) is one threat to sustainable production. Rockström et al (2009) proposes there are nine earth systems that must be kept within boundary limits to ensure a safe planetary system for future generations. Rockström’s identified systems are:
- Climate change
- Ocean acidification
- Stratospheric ozone depletion
- Nitrogen and phosphorus cycles
- Global freshwater use
- Change in land use
- Biodiversity loss
- Atmospheric aerosol loading
- Chemical pollution
Rockström reports three of the nine systems have already exceed his estimated boundary limits; climate change, biodiversity loss and the nitrogen cycle (at the time of his report atmospheric aerosol loading and chemical pollution had not been reported).
Agriculture, with its dependence N for the production of food, fiber and fuel, is a significant contributor to Nr in the environment. Outside of its productive uses the increasing levels of Nr in the environment are leading to environmental concerns. Nitrate, NO3, has long been a concern in ground water, excess Nr contributes to eutrophication and algae blooms in lakes and coastal areas, nitric oxide (NO), and nitrogen dioxide (NO2), collectively referred to as NOx, contribute to smog and haze, nitrous oxide (N2O), is a greenhouse gas with 298 times the global warming potential of carbon dioxide and ammonia (NH3) deposition has been associated with the undesirable changes in forest growth. For more information on N in the environment see What is Reactive Nitrogen and Why Should I Care.